The field of sports racket design has changed dramatically in its recent history. Major improvements in the area of reinforced plastic fabrication have made possible a number of significant improvements in high performance game rackets.
Improved strength of bonding agents and related “co-curing” and “re-curing” molding processes make it possible to have reinforced plastic rackets made up of multiple parts and/or components that can be bonded and/or “co-cured” together to form a racket frame element or a racket frame. Previous concerns regarding the long term durability of multi-part and multi-component construction and its capacity for withstanding the most rigorous performance standards, are no longer a problem. The superior strength that can be achieved is now well beyond that needed for structurally sound, and long lasting products. It's now possible to have not only a high performance multi-part game racket frame, but also to have a high performance game racket frame with a multi-component frame profile.
There are a number of high performance multi-part racket designs currently in use. The term multi-part being used here to describe a racket that is formed of previously molded parts that are bonded together. The parts can be one or a combination of portions including a handle portion and a head portion in order to make a complete racket frame. One good example of this is a design in which a handle portion is molded together with a throat portion in a conventional inflation bladder mold to form one part. That part is then bonded to a head frame part which has also been molded separately in a typical manner. This particular design relies on a rubber gasket to isolate the two parts with the intended purpose being to reduce the amount of shock and vibration transmitted to the handle.
Another multi-part high performance racket design made up of two separate parts bonded together is one in which a head frame portion and a throat portion are molded as one part. That part is then bonded together with a separately molded handle part to form a complete racket frame. This design also uses a rubber gasket for isolation situated between the two parts in order to achieve improved dampening properties.
The same improved bonding agents and related curing processes that make a multi-part frame possible, can also be employed to produce multi-component racket frame profiles. one or more separate, generally tubular components can be “pre-molded”, bonded together and then “re-cured” to form a structurally contiguous, unitary frame profile or, the generally tubular components can also be “pre-formed” together in a mold and “co-cured” to form a structurally contiguous, unitary frame profile. It's also possible to pre-mold a separate component and then co-cure it together with at least one other pre-formed component.
A number of current racket designs can be found having a multi-component frame profile. One in particular is described by U.S. Pat. No. 6,071,203. The frame profile of this game racket is a generally tubular “two-component” design that can be achieved with one of the methods described above. One or both of the two components can be pre-molded, bonded together and then re-cured to make a structurally contiguous unitary frame profile, or the components can be pre-formed together in a mold and then co-cured to form a unitary frame profile. The game racket frame profile by either one of the fabrication methods results in improved racket performance. The common bonding wall between the components forms an internal rib which stabilizes the head frame and stiffens the racket. The result is a larger sweet spot and a more responsive racket.
Improved bonding agents and related curing processes also make one other critical improvement in game racket design possible—“pre-formed” string channel openings. In the previous art of U.S. Pat. No. 6,071,203, joining the two components of the frame profile can result in pre-formed string hole openings or “channels for the strings”, by virtue of their mating configuration. The implications for racket performance are substantial. One very important implication is that the previously accepted method of drilling string holes through a racket frame after it has been molded, can be eliminated. Now openings in the head frame for strings to be laced through as in the conventional way, can be made smooth and therefore protective string grommets can be eliminated too. The resulting stringbed has an enlarged sweet spot due to its capacity for the string to move freely from the outside surface of the head frame profile. The racket is also inherently lean, responsive and easy to balance.
Another method for producing a pre-formed string channel opening that relies on the latest techniques of reinforced plastic fabrication using inflation bladder molding is described by U.S. Pat. No. 6,800,239. The racket as it's described can be made with spacers or “pins” inserted between two pre-formed components and then co-cured in a mold together to form a frame profile with a through channel for the lacing of the strings. The spacers are used to create openings in the flatter portions of the head frame periphery, and the pins are used to create openings on the portions of the head frame periphery through which the strings are often laced at difficult angles. Once again the great benefit is that protective string grommets are made unnecessary due to the controlled fabrication of string hole openings through the head frame profile. The string therefore moves more freely, and the additional weight of a protective grommet can be eliminated.
In spite of the many improvements to racket performance offered by the previous art as derived from these new fabrication techniques, there is one aspect of the potential that hasn't yet been exploited or even cited by the previous art as a potential performance enhancing quality—a game racket frame and/or parts of a frame, and/or components of a frame profile can be made to be substantially fluid tight. Improved bonding agents and related curing processes make it possible to have at least one substantially fluid tight racket frame part or frame profile component, even with strings laced through the head frame in a typical manner. More specifically, no previous art has cited the potential for a game racket with at least one substantially fluid tight part and/or frame profile component, as it relates to a suspension system or sectors of a system located on at least a portion of its head frame and therefore acting directly on the strings. The potential for improving racket performance is significant if a game racket frame with at least one substantially fluid tight portion or alternatively a racket frame with at least one substantially fluid tight part including a handle portion and a head frame portion, could be utilized to inform the spring quality of the stringed hitting area. It would be a further improvement to have a game racket frame with at least one substantially fluid tight portion or a racket frame with at least one substantially fluid tight frame part with strings laced through, that can inform the response characteristics of at least one multi-component spring suspension module located on at least one portion of the head frame to cooperate with at least one string.
If the objective then is to make a game racket with at least one substantially fluid tight part or head frame portion with a generally tubular profile and being laced through with strings in the conventional manner, there is at least one more way to do it that is facilitated by the same fabrication techniques as described above. The string holes of this design are drilled however, as in the previous commonly accepted method, and therefore a protective string grommet is required. The frame profile can have at least two generally tubular components that are spaced apart and away from a string hole location such that when a string hole is drilled through the molded frame, the substantially fluid tight quality of the other component(s) remains intact. Though the responsiveness of the string in this design is generally inferior to a grommetless design, it can have merit, due to its substantially fluid tight potential, in facilitating string suspension designs that rely on fluid retention.
In the context of these vastly improved bonding agents, related curing processes and far more flexible inflation bladder molding techniques, which enable the fabrication of a substantially fluid tight racket part and/or frame profile and frame profile component, even with strings laced through in the conventional manner, significant improvements in string suspension designs that rely on fluid retention can be achieved.
The game racket of U.S. Pat. No. 5,458,331, employs a string suspension system utilizing a fluid chamber to dampen shock, improve the string response, and to adjust the string tension. A number of features of this design make it generally too heavy. One reality of its fabrication using conventional manufacturing methods is drilled string holes. Having string holes that pass through the chamber and the head frame, essentially requires a bladder in order to maintain pressure. The weight and balance are difficult to reconcile and the performance of the racket suffers.
Another unfortunate reality of this design is that in order to maintain bladder pressure, the bladders must be part of a closed loop and therefore continuous around the racket head. Though the continuous chamber is ideal in that it affords a stringbed that is uniformly responsive across its entire surface, the design is hampered by the extra weight of the additional bladder length required. Adding to the complexity of making this design with conventional methods, is the “internal plumbing” required to retain pressure within the racket frame. Not only is the plumbing required to maintain pressure, but it is also required to afford a connection to a conveniently located control means on the frame. It would be a great improvement in the design of sports rackets with string suspension systems to eliminate the “internal plumbing” required for fluid retention and for the accommodation of control means. It would also be advantageous to have a game racket with at least one substantially fluid tight portion and/or part and/or frame profile component, whereby a suspension system, or sectors of a system, can be plugged directly into a fluid retaining vessel that is the racket or at least, a portion or part of a racket. It would also be very beneficial to have a suspension system, or sectors of a system, that plug directly into at least one substantially fluid tight head frame profile component, thereby eliminating the need for a continuous loop around the head frame and providing a means for segregating the interior volume of the generally tubular frame profile. This capacity for segregating the fluid retaining internal volume of the generally tubular frame profile is yet another improvement afforded by new methods that can enable a control means that is conveniently located and implemented with maximum efficiency.
Although one of the novel features of the racket in U.S. Pat. No. 5,458,331 is the adjustable tensioning feature, it is also has drawbacks in its performance. Though the tension of the strings can be changed by adding or withdrawing fluid from the chamber, the magnitude of required pressure is so great that performance adjustment of the racket is limited specifically to changing the string tension alone and not changing the spring quality of the suspension system itself. It would be a truly novel quality in a high performance game racket frame to be able to adjust the stiffness or spring quality of its string suspension system during a pause in play. It would be a great improvement in the design of a string suspension system to have a system or sectors of a system, with adjustable spring characteristics that are attainable by changing the fluid pressure qualities within a substantially airtight racket head frame on which a suspension system or sectors of a system, can be located.
Another string suspension-type design that can rely on pressure retention for its performance traits is the spring element of U.S. Pat. No. 6,971,964. It teaches the benefits of combining a dampening element with a load bearing resilient casing in order to reduce the pressure on the dampening element and therefore to effect more directly, the spring quality of the stringbed. Though the spring response of the element is very good, this design also can be difficult to achieve. The ideal version of the spring element is one that can retain pressure. Because the conventional molding method requires the drilling of string holes through the casing after it's removed from the mold, it's a technological challenge for the spring to retain pressure without either an internal molded cavity which remains intact through the drilling process, or a bladder. And though the internal cavity is achievable by a conventional inflation bladder molding method, it's difficult to control the thickness and therefore the flex response of the internal wall(s). The drilling process of conventional methods also makes it difficult to reduce the weight, requiring protective string grommets be used in the string holes of the outer casing. It would be advantageous over the previous art to have a multi-component, spring suspension module, thereby eliminating the need for a bladder and/or the uncontrollable process of forming an internal wall. It would be another great improvement to have a substantially fluid tight, multi-component, spring suspension module profile that is fabricated with pre-formed string channel openings so that the drilling of string holes through the casing could be eliminated. It would be another great improvement over the previous art to have a multi-component spring suspension module that is fabricated in such a way as to eliminate the additional weight of protective string grommets.
Though the spring element of U.S. Pat. No. 6,971,964 as described is a very effective way to dampen shock at the strings and to enhance the spring quality of the stringbed, there is no mention of its capacity for adjustability. It would be a great improvement over the previous art to have at least one substantially fluid tight, multi-component, generally tubular, spring suspension profile, that is without protective string grommets and that can communicate, i.e. via fluid displacement, with at least one portion of a substantially fluid tight head frame. It would be another improvement over the previous art to have a substantially fluid tight, multi-component, spring suspension module located on at least one substantially fluid tight portion of the head frame such that its stiffness/spring quality can be informed by fluid pressure in the racket.
There is one other issue that plagues any racket frame or racket part requiring the capacity for fluid retention—maintenance. The internal plumbing required in the previous art using conventional fabrication methods is difficult to service if it should spring a leak or if it should happen to come loose inside the tube of a typical frame. If the control means, i.e. valve, should become dislodged in the previous art, it could potentially require replacement of the entire racket frame. It would be a vast improvement over the previous art to eliminate any internal plumbing required for fluid retention. It would be another great improvement to make possible the replacement of one or more individual parts of a multi-part racket frame in order to avoid replacing the entire frame altogether should damage or a malfunction occur.
It is a primary objective of the present invention to improve the performance of a game racket. It is also a primary objective of the present invention to provide a game racket with at least one substantially fluid tight portion or alternatively, a racket with at least one substantially fluid tight part including a head frame, with at least one multi-component, spring suspension module located on at least a portion of a head frame to cooperate with at least one string, that has a weight and balance equal to current high performance racket standards. Another objective of the present invention is to exploit the fluid retention capacity afforded by the latest reinforced plastic molding techniques, as it pertains to a string suspension system or sectors of a system. It is another object of the present invention to exploit the substantially fluid tight potential of a multi-component head frame profile in order to retain fluid pressure while still being laced through with strings. Another object of the present invention is to provide at least one dependent spring suspension module, on the head frame of a fluid pressure retaining racket wherein its spring quality can be informed by fluid pressure in the racket. It is yet another object of the invention to provide a control means by which the pressure in at least one portion of the racket, or at least one part of the racket frame, can be changed, which subsequently changes the stiffness of at least one spring suspension module located on at least one portion of the head frame. Another object is to provide a fluid retaining game racket with strings laced through, that can communicate with at least one substantially fluid tight multi-component spring suspension module mounted on at least one portion of its head frame. It is another object of the present invention to provide a racket with at least one multi-component spring suspension module, that is free of extraneous parts and has optimum overall balance characteristics in keeping with the highest performance standards to date. Still another object is to provide at least one multi-component spring suspension module located on at least one substantially fluid tight portion of the head frame whose performance is not hindered by conventional stringing methods.
To achieve these objects, a game racket including at least one substantially fluid tight portion including a handle and a head frame is provided. Alternatively, a game racket with at least one substantially fluid tight part comprised of at least a handle portion and a head frame portion, can be provided. The head frame has at least one substantially fluid tight portion and has strings laced through and held in tension to form a stringed hitting surface. At least one multi-component, spring suspension module is located on at least one portion of the head frame to cooperate with at least one string. The racket frame and the racket frame profile, can be made from at least one part and/or at least one component and then joined together to form a substantially fluid tight game racket frame. At least one substantially fluid tight portion of the head frame can receive and communicate with, at least one multi-component, spring suspension module. The at least one spring suspension module has a profile comprised of at least two generally tubular components with at least one common wall and utilizes the latest techniques of inflation bladder molding.